Hydrocarbon composition containing polyalkyl-substituted tetrahydro-naphthalenes and di-n-c10-c15-alkaryl hydrocarbons and process for preparing same

ABSTRACT

HYDROCARBON COMPOSITION CONTAINING AT LEAST 20 VOLUME PERCENT POLYALKYL-SUBSTITUTED TETRAHYDRONAPHTHALENES AND FROM 25 TO 60 VOLUME PERCENT DI-N-C10-C15-ALKARYLS, EACH OF SAID TETRAHYDRONAPHTHALENES AND SAID DI-N-C10-C15-ALKARYLS CONTAINING FROM 26 TO 36 CARBON ATOMS. PROCESS FOR PREPARING SAID HYDROCARBON COMPOSITION, WHEREIN THE PROCESS COMPRISES (1) CONTACTING AN ADMIXTURE OF MONON-C10-C15-ALKARYLS AND ALKYL-SUBSTITUTED TETRAHYDRONAPHTHALENES WITH A FRIEDEL-CRAFTS CATALYST, AND (2) FRACTIONALLY DISTILLING THE REACTION MASS TO RECOVER THE DESIRED HYDROCARBON COMPOSITION. THE HYDROCARBON COMPOSITION IS SUITABLE FOR USE BOTH AS A FEEDSTOCK FOR PREPARING OIL-SOLUBLE SLUFONIC ACIDS AND AS A LUBRICANT, PARTICULARLY A LUBRICANT FOR LOW-TEMPERATURE AMBIENT CONDITIONS.

United States Patent Oflice 3,661,780 HYDROCARBON COMPOSITION CONTAININGPOLYALKYL-SUBSTITUTED TETRAHYDRO- NAPHTHALENES AND DI-n-C -C -ALKARYLHYDROCARBONS AND PROCESS FOR PRE- PARING SAME George C. Feighner,Franklin Lakes, N.J., and Oliver C. Kerfoot, Delmar D. Krehbiel, andGene E. Nicks, Ponco City, Okla, assignors to Continental Oil Company,Ponca City, Okla.

No Drawing. Continuation-impart of application Ser. No.

716,351, Mar. 27, 1968, which is a continuation-inpart of applicationSer. No. 643,370, June 5, 1967, both now abandoned. This applicationOct. 26, 1970, Ser. No. 84,125

Int. Cl. C10m 1/16 U.S. Cl. 252-59 11 Claims ABSTRACT OF THE DISCLOSUREHydrocarbon composition containing at least volume percentpolyalkyl-substituted tetrahydronaphthalenes and from to 60 volumepercent di-n-C -c -alkaryls, each of said tetrahydronaphthalenes andsaid di-n-C -C -alkaryls containing from 26 to 36 carbon atoms. Processfor preparing said hydrocarbon composition, wherein the processcomprises (1) contacting an admixture of monon-C -C -alkaryls andalkyl-substituted tetrahydronaphthalenes with a Friedel-Crafts catalyst,and (2) fractionally distilling the reaction mass to recover the desiredbydrocarbon composition. The hydrocarbon composition is suitable for useboth as a feedstock for preparing oil-soluble sulfonic acids and as alubricant, particularly a lubricant for low-temperature ambientconditions.

CROSSREFERENCE TO RELATED APPLICATIONS The present application is acontinuation-in-part of application Ser. No. 716,351, filed Mar. 27,1968, now abandoned which in turn was a continuation-in-part ofapplication Ser. No. 643,370, filed June 5, 1967, and now abandoned.

BACKGROUND The present invention relates, in one aspect, to hydrocarboncompositions which are especially suitable as feedstocks for preparingoil-soluble sulfonic acids and sulfonates and which comprises a mixtureof di-n-C -C -alkaryls and polyalkyl-substituted tetrahydronaphthalenes.In a second and preferred aspect, the present invention relates to aprocess for preparing the hydrocarbon compositions of the aforementionednature by the disproportionation of a mixture of alkyl-substitutedtetrahydronaphthalenes and mono-n-C -C -alkaryls.

Oil-soluble sulfonic acids are particularly useful in modern technology.As the metal salts (particularly sodium, barium, calcium, and magnesiumsalts) they are used in lubricating oils, metal working oils, solubleoils, and rust inhibitors. Highly basic additve agents, derived fromoil-soluble sulfonic acids and containing dispersed barium, calcium, ormagnesium compounds, are particularly useful in lubricating oils andmarine diesel lubricants.

One of the earliest methods of producing oil-soluble sulfonic acids wasthat of treating aromatic-containing petroleum fractions with sulfuricacid. The sulfonates so produced, upon conversion to sodium salts, wereknown to the trade as mahogany sulfonates. In general, these sulfonateswere a by-product of the manufacture of lubricating oil base stocks orwhite oils. Inasmuch as they were a by-product, the supply of thematerials was related to the amount of lubricating oil base stocks whichwere acid treated. The development of improved methods of preparinglubricating oil base stocks has substantially reduced the supply ofmahogany sulfonates.

More recently, synthetic feedstocks have been used to prepareoil-soluble sulfonic acids. The synthetic feedstocks are hydrocarbonfractions containing substantial amounts of alkyl-aromatic compoundswhich sulfonate readily. An example of a particularly satisfactorysynthetic hydrocarbon feedstock for preparing oil-soluble sulfonic acidsis postdodecylbenzene, which is a by-prodnot of the preparation ofdodecylbenzene. While postdodecylbenzene is quite satisfactory as afeedstock for preparing oil-soluble sulfonic acids, it has thedisadvantage that the availability thereof is tied directly to theproduction of dodecylbenzene.

In order for a hydrocarbon feedstock to be particularly usefulcommercially for the preparation of oil-soluble sulfonic acids, it mustpossess certain requisites. First, it must have a molecular Weight ofsufficient magnitude that the sulfonic acids thereof are readilyoil-soluble. Usually, this means a molecular weight of at least about350, but preferably of at least about 400. Secondly, the hydrocarbonfeedstock must sulfonate readily. This feature is a function of thechemical nature of the feedstock. Thirdly, it must be relativelyinexpensive. The present invention is concerned with a hydrocarbonfeedstock which meets all of the foregoing requisites.

In addition to being useful as a feedstock for preparing oil-solublesulfonic acids, the hydrocarbon compositions of the present inventionhave properties which render them useful as lubricants, and particularlyas lubricants under low-temperature ambient conditions. Because of theirphysical properties the hydrocarbon compositions described herein can beused as the base oil to formulate crankcase lubricants, automatictransmission lubricants, hydraulic fluids, circulating fluids, and avariety of other lubricants for low-temperature service.

PRIOR ART No references were cited against the claims in the parentapplication directed to the hydrocarbon composition, or process ofpreparing the hydrocarbon composition, described herein.

BRIEF SUMMARY OF THE INVENTION Broadly stated, one aspect of the presentinvention concerns a process for preparing a hydrocarbon composition,wherein the process comprises:

(a) Contacting an admixture of alkyl-substituted tetrahydronaphthalenesand mono-n-C -C -alkaryls with a Friedel-Crafts catalyst underreaction-promoting conditions of temperature and time whereby there isproduced a product containing at least about 20 volume percent,preferably at least about 30 volume percent, of a hydro carbon mixtureconsisting essentially of di-n-C -C -alkaryls and polyalkyl-substitutedtetrahydronaphthalenes, said tetrahydronaphthalenes containing from 26to 36 carbon atoms and said di-n-C -C -alkaryls containing from 26 to 36carbon atoms, and

(b) Fractionally distilling the reaction mass of step (a) to recovertherefrom a bottoms fraction containing at least about 45 volumepercent, preferably at least about volume percent, of a hydrocarboncomposition consisting essentially of from about 25 to about 60 volumepercent, preferably from about 25 to about 55 volume percent, di-n-C -C-alkaryls and at least 20 volume percent polyalkyl-substitutedtetrahydronaphthalenes, said tetrayhdronaphthalenes containing from 26to 36 carbon atoms and said di-n-alkaryls containing from 26 to 36carbon atoms.

In another aspect, the present invention relates to a hydrocarboncomposition, containing at least 20 volume percent linearpolyalkyl-substituted tetrahydronaphthalenes and from about 25 to about60 volume percent, preferably from about 25 to about 55 volume percent,di-n-C -C -alkaryls, said tetrahydronaphthalenes containing from 26 to36 carbon atoms and said di-n-alkaryls containing from 26 to 36 carbonatoms. Preferably, the total of the tetrahydronaphthalenes anddi-n-alkaryls is at least about 75 volume percent of the hydrocarbonfraction. The hydrocarbon fraction distills above about 204 C. at 10 mm.Hg, preferably above about 220 C. at 10 mm. Hg.

In still another aspect, the present invention relates to oil-solublesulfonic acids derived from a hydrocarbon composition consistingessentially of di-n-C -C -alkaryls and linear polyalkyl-substitutedtetrahydronaphthalenes, said tetrahydronaphthalenes containing from 26to 36 carbon atoms and said di-n-C -C -alkaryls containing from 26 to 36carbon atoms.

In yet another aspect, the present invention relates to highly basicbarium, calcium or magnesium sulfonates prepared from oil-solublesulfonic acids derived from a hydrocarbon composition consistingessentially of di-n- C -C -alkaryls and polyalkyl-substitutedtetrahydronaphthalenes, said tetrahydronaphthalenes containing from 26to 36 carbon atoms and said di-n-alkaryls containing from 26 to 36carbon atoms.

DETAILED DESCRIPTION Our process can be illustrated by the followingreactions which occur simultaneously:

I E Z n! R, R, R", and R" will be characterized in our description ofsuitable starting materials.

While the above reactions produce the desired product mixture, sidereactions occur which produce materials such as branched parafiins,naphthalenes, miscellaneous polycyclic compounds, sludge, etc.

In order to achieve good selectivity, partial conversion per pass ispracticed. The upper limit per pass is about 60-70 percent, with thepreferred conversion per pass being about 4050 percent.

The material which is used in our process is an admixture consistingessentially of alkyl-substituted tetrahydronaphthalenes and mono-n-C -C-alkaryls. The alkylsubstituted tetrahydronaphthalenes have thefollowing formula:

where R and R" are linear alkyl groups, each of which contains from 1 to10 carbon atoms, with the sum of the carbon atoms in R and R" being from6 to 11, and where R' is hydrogen or an alkyl group containing from 1 to3 carbon atoms. Preferably, R'" is hydrogen. The term linear alkylgroups are used herein refers to alkyl groups which are free of chainbranching.

The mono-n-C -C -alkaryl hydrocarbons are represented by the formula:

where R is a linear alkyl group containing from 10 to 15 carbon atomsand R" is hydrogen or an alkyl group containing from 1 to 3 carbonatoms. The preferred monoalkaryl hydrocarbons are monoalkylbenzeneswherein the alkyl group is linear and contains from 10 to 15 carbonatoms.

It should be noted that the polyalkyl-substituted tetrahydronaphthaleneof our product have the formula:

RIII

fill

where These polyalkyl-substituted tetrahydronaphthalenes are present inthe hydrocarbon composition in an amount of at least 20 volume percent,more suitably at least 2 8 volume percent, and preferably at least 45volume percent.

A particularly suitable material for use in our process is a by-productfraction of a process for preparing biodegradable detergents describedin US. Pat. No. 3,316,294. For reason of convenience, this patent ismade a part of the present application. Briefly, Pat. No. 3,316,294relates to a process of preparing a detergent alkylate wherein theprocess comprises the following steps, broadly stated: (a) separating afraction of substantially straight chain C c hydrocarbons from apetroleum distillate substantially free of olefins and containing saidstraight chain hydrocarbons together with non-straight chainbydrocarbons, (b) chlorinating said fraction to the extent wherebybetween about 10 and about 35 mole percent of the straight chainhydrocarbons present are substantially only monochlorinated, and (c)alkylating an aromatic compound, selected from the group consisting ofbenzene, a C -C alkyl-substituted benzene and mixtures thereof, with thechlorination product of step (b) in the presence of an alkylationcatalyst.

In conducting our process, the alkyl-substituted tetrahydronaphthalenesand mono-n-C -C -alkaryls, suitably, are present in the range of about3:1 to about 0.15:1, expressed as tetrahydronaphthalenes:alkaryls.Preferably, this ratio is from about 1:1 to about 0.33:1. Morepreferably, it is about 0.33:1.

Moreover, in conducting our process, preferably, the alkyl-substitutedtetrahydronaphthalenes and the monon-C -C -alkaryls, used as chargematerials, have approximately the same number of total carbon atoms.

Any of the Friedel-Crafts catalysts can be used in our invention. Theterm Friedel-Crafts catalyst is believed to be well understood in theart and refers in general to materials such as the aluminum halides,boron trifiuoride, boron trichloride, antimony chloride, stannicchloride, zinc chloride and mercuric chloride. Of the FriedelCraftscatalysts, aluminum chloride is preferred. The preferred material,aluminum chloride, also includes insitu prepared aluminum chloride, inother words, the reaction product of aluminum metal and hydrogenchloride.

A suitable amount of Friedel-Crafts catalyst is from about 0.5 to aboutpercent by weight, with a preferred amount being from about 2 to about 4percent by weight, based on the total amount of monoalkaryls andtetrahydronaphthalenes in the charge admixture. It is to be understoodthat larger amounts than those stated in the foregoing can be used.However, from a practical viewpoint, the use of larger amounts is noteconomical.

Conventionally a proton-donor promoter is used with a Friedel-Craftscatalyst. Suitable promoters include any material which, when added tothe catalyst, yields a proton. Preferred promoters are hydrogen chlorideand water. When a promoter is used, only a trace is required. Theselection of the amount of promoter can be made readily by those skilledin the art.

Conditions of temperature and time are not a critical feature of ourinvention. We have found a temperature in the range of from about 45 toabout 150 C. to be satisfactory. Still further, on a batch basis, wehave found reaction times of from about 15 minutes to about 2 hours tobe satisfactory. It is believed that any person skilled in this art,knowing the other features of our invention can, without undue orprolonged experimentation, determine the desirable conditions of timeand temperature.

While we have usually operated our process on a batch basis, we havealso operated on a continuous basis.

The hydrocarbon composition is converted to oilsoluble sulfonic acids bytreatment with a suitable sulfonating agent (e.g., oleum or sulfurtrioxide). Using conventional techniques our hydrocarbon compositionresult in a good qualitv oil-soluble sulfonic acid in a yield up toabout 1.10 pounds sulfonic acid per pound of alkylate (theoreticalyield: 1.20).

The oil-soluble sulfonic acid is converted to oil-soluble metalsulfonates by treatment with bases containing the desired cation usingconventional techniques.

Also, the oil-soluble sulfonic acids are converted to a highly basicbarium-containing additive agent by the process of US. Pat. No.2,861,951. Briefly, the process comprises:

(A) admixing under atmospheric conditions of temperature and pressure:

(1) an oil-soluble sulfonic acid and a volatile solvent therefor (e.g.,naphtha),

(2) a non-volatile carrier (e.g., mineral lubricating (3) a methanolicsolution of barium oxide;

(B) converting the barium oxide to barium carbonate in situ in thepresence of the sulfonic acid by blowing with carbon dioxide;

(C) removing the volatile solvents and any water present.

For reason of convenience, US. Pat. No.2,861,951 is made a part of thisapplication. In addition, it is to be understood that, with theexception of dispersing agents, the broad aspects of the processdisclosed in this patent are applicable to the process describedimmediately above.

Still further, the oil-soluble sulfonic acids are converted to a highlybasic calcium-containing additive agent by the process of U5. Pat. No.3,150,088. Briefly, the process comprises:

(A) admixing:

(1) an alcoholic solution of a calcium alkoxide-carbonate complexwherein the alkoxide radical is derived from a monoether alcohol ofethylene glycol,

(2) oil-soluble sulfonic acid,

(3) non-volatile carrier (e.g., mineral lubricating oil),

(4) water in an amount which is a stoichiometric excess of that requiredto react with the calcium alkoxide-carbonate complex;

(B) hydrolyzing the calcium alkoxide-carbonate complex to anoil-insoluble calcium-containing inorganic compound; and then (C)removing the volatile materials.

For reason of convenience, US. Pat. No. 3,150,088 is made a part of thisapplication. In addition, it is to be understood that, with theexception of dispersing agents, the broad aspects of the processdisclosed in this patent are applicable to the process describedimmediately above.

ILLUSTRATIONS AND COMPARISONS Example 1 Fifty parts by weight of lineardialkyl tetrahydronaphthalene (C tetrahydronaphthalene distilled from aC side chain alkylate and 50 parts by Weight of monoalkylbenzene (C sidechain external alkylate distilled from a C alkylate were charged to aflask. The mixture was heated to C., then 3.0 parts AlCl and a trace ofwater were added. The mixture was stirred under these conditions andsamples were taken as the reaction progressed. The samples showed thefollowing:

Percent Monoalkyl- Tetrahydrobenzene naphthalene Overall convertedconverted conversion The product was distilled to remove unreactedmaterial. The material distilling above 204 C. at 10 mm. Hg pressure wasdesired product fraction. A sample of the product fraction was analyzedby mass spectrometer, the results of which are shown in Table I.

Example 3 Fifty parts by weight of linear dialkyl tetrahydronaphthalenes(C tetrahydronaphthalene distilled from a C side chain alkylate and 50parts by weight of monoalkylbenzene (C side chain fraction distilledfrom a C total alkylate were charged to a flask. This mixture was heatedto 100 C., then 2.0 parts by weight AlCl and a trace of HCl were added.The mixture was stirred under these conditions and samples were takenProduced by the process of Pat. No. 3,316,294-fraction distilling at-204" C. at 10 mm. Hg.

Produced by the process of Pat. No. 3,316,294f1'act1on distilling at191-195 C. at 10 mm. Hg.

as the reaction progressed. The samples showed the following:

TABLE I.MASS SPECTROMETER ANALYSIS OF PRODUCT OF EXAMPLE 2 n Zn-S) nzn-fi) n 2n14) n zn!2) Tetrahydro- Dialkyl- Diphenyl Naph- Carbon number(Cn 2n-l0) naphthalenes benzenes (CnHQn-lfi) alkano thalenes 0. 1 0. 30. 1 0. 4 0. 5 0. 6 0. 6 0. 9 2. 6 o. 3 0. 1 2. 1 0. 3 0. 1 2. 4 0. 3 0.1 2. 0 0. 3 0. 1 l9. 9 l. 7 2. 0 1. 9 0. 2 0. 2 0. 4 0. 3 0. 3 0. 3

Percent Product M n 1k T H h dr 'SUIfOIllC acid solution 0 0a ye a yobenzene naphthalene Overall 5 Parts 1283 Time converted convertedconversion Total acid, meq./ g. 0.919 0 0 0 Sulfonic acid, meg/g. 0.5281 & Combining weight 483 12: 2 0 15: 8 i l g- RSO H/galkylate 1.07 12. 921'. 1 16. 7 18. 0 25. 8 21. 5 23. 3 a2. 0 27. 4 Example 5 26. 7 43. 42.O

The product was distilled to remove unreacted material. The materialdistilling above 204 C. at 10' mm. Hg pressure was the desired productfraction. A sample of the' product fraction was analyzed by massspectrometer, the results of which are shown in Table II.

This example illustrates the preparation of a highly basicbarium-containing additive agent using the hexane solution of sulfonicacid prepared in Example 4.

Procedure: The procedure used was that of US. Pat. 2,851,951, describedin the foregoing.

TABLE II.--MASS SPECTROMETER ANAYLSIS OF PRODUCT OF EXAMPLE 3 Liquidvolume percent (cure-s) (curler) (cum-1;) Tetrahydro- Dialkyl- DiphenylCarbon number (0 nH'l -IO) naphthalenes benzenes (CnHEn-H) alkanesNaphthalenes Totals--.- 0.9 55.5 27.4 3.9 4.2

Example 4 Charge: =Parts This example illustrates the preparation ofoil-soluble Sulfonic acid 250 sulfonic acid from a product similar tothat of Example 2. 100 pale oil 17.9 Procedure: The hydrocarboncomposition (feedstock) M th lj g 1 143 was sulfonated with 20 percentoleum using a 1.5 :1 Weight ratio of oleumzhydrocarbon in 100 pale oilas a diluent at 50-55 C. After taking a primary sludge split, the crudeacid oil was diluted with hexane and allowed to settle overnight. Atthis point a second split was taken. A small portion of the crudeacid-oil was taken for analysis. The remaining hexane-sulfonic acidsolution was purified by treatment with lime and blowing with nitrogengas.

1 The alkylate had the following analysis Molecular weightDialkylbenzencs, percent Trialkylated tetrahydronaphthalenes, percentDiphenylalkanes, percent Naphthalenes, percent 2 '1E,he methanolicsolution of BaO had a base number of Product: There was obtained 149.9parts of a product (theory=153.1 parts) having the following properties:

Ba'se No. (acetic) '69 Ba sulfonate, percent 49 Viscosity, 210 F., cs.25.03

Example 16 The process was similar to that of Example 2, using thefollowing specific conditions:

100 (3.: temperature 1.5 hr.: residence time 3% Alcl -l-water promoter:catalyst The material distilling above 205 C. at mm. Hg was the desiredproduct fraction.

The product fraction had the following analysis by mass spectrometer:

Percent Dialkyl tetrahydronaphthalenes 3.3 Trialkyltetrahydronapthalenes36.3 Dialkylbenzenes 52.9 Diphenylalkanes 4.2 Alkylated naphthalenes 3.1

Sulfonation of the product fraction gave a yield of 1.13 pounds ofoil-soluble sulfonic acid per pound of product fraction.

The process gave a 35% conversion of the feed alkylate and a yield of0.58 pounds of desired product per pound of alkylate consumed.

The following table illustrates the boiling range, at 10 mm. Hgpressure, of many of the components present in our starting mixture. Thetable also illustrates the boiling range of the dialkylbenzenes andtrialkyl-substituted tetrahydronaphthalenes of the product fraction.

TABLE III Boiling range at 10 mm. Hg, C.

Dialkyl- Dlalkyl benzene plus Monoalkyltetrahydrotrialk Alkyl side chainbenzenes naphthalenes naphthalenes 1 Initial boiling point.

where R and R" are linear alkyl groups, each of which contains from 1 to10 carbon atoms, with the sum of the carbon atoms in R and R" being from6 to 11, and R is hydrogen or an alkyl group containing from 1 to 3carbon atoms, and (B) alkaryl hydrocarbons represented by the formulawhere R is a linear alkyl group containing from 10 to carbon atoms andR' is hydrogen or an alkyl group containing from 1 to 3 carbon atoms,said (A) and (B) being present in the admixture in a proportion in therange of from about 3 :1 to about 0.15:1 of (A) to (B) on a Weightbasis, with an effective amount of a Friedel-Crafts catalyst underreactionpromoting conditions of temperature and time whereby there isproduced a product containing at least about 20 volume percent of ahydrocarbon mixture consisting essentially of di-n-C -C -alkyls andpolyalkyl-substituted tetrahydronaphthalenes, saidtetrahydronaphthalenes containing from 26 to 36 carbon atoms and saiddialkaryls containing from 26 to 36 carbon atoms; and

(b) fractionally distilling the reaction mass of step (a) to recovertherefrom a fraction distilling above about 204 C. at 10 mm. Hg pressureand containing at least 75 volume percent of a hydrocarbon mixtureconsisting essentially of di-n-C -C -alkaryls and polyalkyl-substitutedtetrahydronaphthalenes, said tetrahydronaphthalenes contaning from 26 to36 carbon atoms and said dialkaryls containing from 26 to 36 carbonatoms.

2. The process of claim 1 wherein the polyalkyl-substitutedtetrahydronaphthalenes of the product fraction of step (b) arerepresented by the formula:

wherein R, R, and R" are linear, and

R contains from 10 to 15 carbon atoms, R contains from 1 to 10 carbonatoms, R" contains from 1 to 10 carbon atoms,

with the sum of R and R" being in the range of from 6 to 11, and whereinR'" is hydrogen or an alkyl group containing 1 to 3 carbon atoms.

3. The process of claim 2 wherein the polyalkyl-substitutedtetrahydronaphthalenes and the alkaryl hydrocarbons are present in theratio of from about 1:1 to about 0.33:1.

4. The process of claim 3 wherein the Friedel-Crafts catalyst isaluminum chloride and is present in an amount in the range of from about0.5 to about 5 percent, by weight.

5. The process of claim 4 wherein the process is conducted at atemperature in the range of from about 45 to about C.

6. The process of claim 5 wherein R of the alkaryl hydrocarbon and thetetrahydronaphthalene starting material of step (a) is hydrogen.

7. A hydrocarbon composition containing at least 28 volume percentpolyalkyl-substituted tetrahydronaphthalenes and from about 25 to about60 volume percent di-n- C -C -alkaryls, said tetrahydronaphthalenescontaining from 26 to 36 carbon atoms and said dialkaryls containingfrom 26 to 36 carbon atoms.

8. The hydrocarbon composition of claim 7 characterized further in thatthe polyalkyl-substituted tetrahydronaphthalenes are represented by theformula:

wherein R, R, and R" are linear, and

R contains from 10 to 15 carbon atoms, R' contains from 1 to 10 carbonatoms, R contains from 1 to 10 carbon atoms,

with the sum of R and R" being in the range of from 6 to 11, and whereinR" is hydrogen or an alkyl group containing 1 to 3 carbon atoms.

9. The hydrocarbon compoistion of claim 8 wherein the di-n-C -C-alkaryls are di-n-C -C -alkylbenzenes.

10. The hydrocarbon composition of claim 9 wherein the amount of di-n-C-C -alkylbenzenes is from about 25 to about 55 volume percent.

11. The hydrocarbon composition of claim 10 characterized further inthat the total of the tetrahydronaphthalenes and dialkylbenzenes is atleast 75 volume percent.

1 2 References Cited UNITED STATES PATENTS DANIEL E. WYMAN, PrimaryExaminer 10 W. H. CANNON, Assistant Examiner US. Cl. X.R.

